Rotary tiller



' A. SCHMIDT ET AL ROTARY TILLER 7 April 5, 1932.

Filed Dec. 2, 1930 2 Sheets-Sheet 1 Patented Apr; 5, 1932 UNITED. STATES PATENT OFFICE ADOL]? SCHMIDT, OF BERLIN-CHARLOTTENBURG, AND GEORG PENEFF, OF BERLIN- WILMERSDORF', GER-MANYI, ASSIGNORS TO SIEMENS-SCHUCKEIRTWERKE AKT'IEN- GESELLSCHAFT, OF BERLIN-SIEMENSSTADT, GERMANY, A CORPORATION OF GER- MANY ROTARY TILILER Application filed Decembdr 2, 1930, Serial No. 499,441, and in Germany October 21, 1929.

' tool springs are particularly in hard ground or in ground containing large stones, bent excessively and break owing to premature fatiguing of the material.

Means have already been tried to avoid these drawbacks. Rigid stops have, for instance, been provided with the object of preventing the tool springs being bent too-much. Stops of that kind are, however, not very advantageous, as the impact of the tool against hard objects causes heavy shocks to the rotary tiller.

It has also been proposed to arrange springs as stops on the shaft carrying the tools and by this means to render the action of the stop upon the tool spring proper elastic within a certain limit. But this arrangement did-not prove very successful either, as the springs acting as stops were often destroyed when greater obstacles were encountered in the work. When once the stop-springs were dest oyed, the tool-springs broke in a short time owingto their being then very much overstrained. The employment of springs for this purpose was altogether not favorable, because arrangements consisting of springs have-to be comparatively large if the springs areto be capable of bending sufficiently when the force exerted upon them is large. The fixing of a spring arrangement is particularly diflicult if guide forks are used to prevent a i lateral swinging of the working hook, etc.

Our invention consists in the provision of elastic unbreakable buffers for damping and limiting the bending of the tool springs, said buffers being'so made that the elastic countor-force exerted by the bufier increases to a greater degree than thecompression produced so by the tool.

The invention consists further in .piece the buffer of rubber and in arranging it betweenthc prongs of a guide fork serving to I, secure thc'working tool against lateral dcflection.

The invention consists still further in the provision of a special guide piece or member hcldon the prongs of the guide fork at the end of the rubber buffer.

The rubber hl'llfers have the advantage over the above mentioned devices that the resisting counterforce produced by compression in the buffer is not proportional to the force exerted on the tool, but increases to a considerably greater degree than the force on the tool. Consequently, after a certain compression of the rubber buffer is reached, the damping counterforce the buffer exerts on the tool increases to such a degree thatthe' tool cannot yield any further. The rubber bufier has, however, still a damping effect so that hard jolts or shocks onthe rotary tiller are avoided.

Fig. 1 shows a section through a tilling or toolshaft of a rotary tiller with an elastical- 1y fixed tool and a rubber buffer according to t .e invention. The rubber buffer is arprongs of a guide fork,

ranged between the furnished to prevent a lateral swinging of the tilling tool.

In Fig. 2 is represented a cross section through theguide fork and the rubber buffer for a tilling tool according to Fig. 1.

Figs. 3 and 4 show a cross section through the tilhng shaft and the guide fork above the rubberbufi'er in an improved construction, in which; a metal plate serving as a guide or member is provided at the end of the buffer.

Fig. 5 represents a similar construction. The guide piece is, however, not made in plate-form but as a hood or cap.

Figs. 6 and 7 show shapes of the guide fork or the rubber bufler, in which the deformation of the rubber bufier to be expected is taken into consideration, and

In Figs. 8 and 9 are illustrated a radial and an axial section throughthe shaft of a I rotary tiller, in which the clamping device carrylng the tilling tool and coming into contact with the rubber buffer, is situated spring immediately between the prongs of the guide fork, the latter conforming in shape to the movements of the tilling tool.

In Fig. 1, the numeral 1 indicates the tilling shaft, which is driven by a motor drive not shown on the drawings. Onto the shaft, the hub 2 is fastened and provided with alug to fix the tool spring 5. In the drawings, pnly one tool spring is represented. For field service, however, tool springs would also be fastened to other lugs. The number of tools arranged next to one another round the circumference of the tool shaft is immaterial for the essence of the invention. Three or more tools may be distributed and arranged round the circumference of the shaft. Each spring carries at its end an exchangeable tilling hook 6. On the hub 2 behind each tool a rubber buffer 7 is mounted. The rubber buffer is so placed behind the exchangeable tilling hook as to dampen the bending of the spring whenreceding. It is held between the two prongs of a fork 9, arranged on the hub 2 and serving to prevent the lateral deflection of the resilient tool hook. The arrangement of the rubber buffer 7 may be better seen from the cross section represented in Fig. 2. The rubber buffer is so shaped that the two prongs of the fork 9 lie in two grooves of the buffer and that consequently slipping out of the buffer from between the fork is prevented. I

An improved arrangement of therubber buffer may be obtained according to Figs. 3 and 4 by providing at the end of the rubber. buffer a specially formed plate-shaped piece 10 having recesses into which are placed the prongs of the guide fork 9. The tool 6 receding when forces are exerted on it, lays itself against the guide piece 10, which slides securely between the prongs of the fork 9.

The rubber buffer is held at its other end bya back stop 8 fastened directly to the tool holder. It is preferable for the rubber buffer 7 to be set into the guide piece 10 and also into the back stop 8. The buffer 7 may be connected to the parts 8 and 10 made of metal. The rubber buffer may also be provided with special guide grooves in a similar manner to that shown in Fig. 2. These guide grooves may, however, be made less deep, as the guiding is mainly done by the guidemember 10.

Fig. 5 shows The guide piece 10 does not consist of a plate but has the shape of a hood or cap. When the working hook comes up against the guide piece 10, it oniy touches it on a small contact surface. Thereby a reduction of the friction between the working hook 6 and the guide piece 10 is obtained. In this figure, 11 indicates the recesses in the guide hood 10, in which the prongs of the guide fork 9 can slide. The rubber buffer is also provided with a shallow guide groove 12.

a somewhat different shape} further lugs 23, into which the two ends 22 When the rubber buffer is pressed together by the tool on the striking of an obstruction by the latter it is greatly deformed and thereby so squeezed in between the guide fork that a permanent deformation of the rubber body may result. To avoid this, the rubber body or the guide fork may be given a shape preventing a dangerous compression of the rubber body between the prongs of the fork. In Fig. 6 the rubber body provided with guide grooves 12 is in the middle narrower than at the ends. WVhen the body is pressed together by the working tool, the middle part then expands more than the ends, so that the body assumes approximately the shape of the prongs of the fork.

The same result is obtained if according to Fig. 7 the buffer is given an approximately cylindrical shape and the lower ends of the prongsof the fork 9 are bent outwardly as shown in Fig. 7.

lVith the aforedescribed constructions, the tool is so designed that the-hook-shaped tool comes up against the buffer or the guide piece connected to the buffer.

The arrangement may, however, also be made so that the spring carrying the tool hook comesv up against the rubber buffer or against -the guide piece connected to the buffer.

Figs. 8 and 9 show another construction, in which the clamping member serving to connect the spring 5 with the tool 6 comes up against the buffer. The clamping device slides directly in the guide fork 9 and puts itself, when the tool is bent back, against a guide plate 19 at the end of the rubber buffer. The end plate 19 is provided with .holes through which the prongs 9 of the guide fork are passed. In the end plate 19 is arranged a recess 20, into which the round part of the clamping member 13 fits, thus making it more difficult for the clamping member 13 to move sideways when once the tool is bent back and is in contact with the buffer. By this means the pressure between the clamping member and the guide fork is relieved. The clamping member 13 for fastening the tool is so designed that by means of screws the loop-shaped end of the tool spring and also the tool 6 are tightly clamped.

In Figs. 8 and 9 an advantageous manner of fastening the guide fork 9 is also illustrated. On the hub 2 a rib-shaped lug 21 is provided. Over this lug 21 a U-shaped angle iron 14 is slipped. Through two holes drilled into the web of the U-iron 14, are passed the prongs of the guide fork 9 forming a loop and lying between the upper flange of the U-iron and the rib-shaped lug 21. By means of a screw 15 the U-iron 14 is fastened by one of its flanges to the rib-shaped lug 21. At the side of the rib 21 on the hub 2, and, if desirable, connected to the rib 21, are two of the tool spring are introduced through 1 drilled holes. The U-iron 14 .is further furnished with2 lugs 17, cut out of the Uiron itself and bent up against the surface of the 5 lugs 23 and against the ends 22 of the tool springs held in the lugs; the ends of the tool springs being thereby prevented from slipping through the fastening lugs 23. A back stop 18 takingthe rubber buffer 7 is 10 rigidly connected to the U-iroii 14. An adv tageous manner of making this connec tion is by welding the two parts together.

If instead of the angle iron 14 a suitable casting is used, the rubber liuifer may be 15 arranged to rest in this casting.

The rubber buffers according to the present invention have proved to be exceedingly advantageous. When great obstructions are encountered, the rubber bufi'ers damp the receding motion of the resiliently fastened tools and prevent, w en shocks occur, the tools or the springs from being broken. The buffers form a simple constructional part taking but little room and being unbreakable. In existing rotary tillers rubber buffers can be subsequently installed by simple means.

The invention is not limited to the embodiments illustrated in the drawings and described in the specification, but modifications and changes may be made without departing from the spirit and scope of the invention as defined in the following claims. We claim as our invention:

1. In connection with an elastically yielding tool for rotary tillers the arrangement of i a rubber buffer as a damper in combination with a guide fork, fastened to the hub of said tool, suitable for preventing lateral deviations of tool.

ing tool for rotary tillers the arrangement 0 a rubber buiferas a damper in combination with a guide fork fastened to the hub of said tool, suitable to prevent the lateral deviation of the tool, said rubber bufi'er being provided with grooves in which lie the prongs of the guide fork.

. 3. elastically yielding tool for rotary tillers, consisting of a working book, a spring connected with said hook, said spring being fastened to a hub connected to the driving shaft, in combination with a rubber buffer as a damper for the spring and a guide fork as a lateral guide, said rubber buffer being provided with a guiding member atone end go guide it along the prongs of the guide or 5 4.'An elastically yielding tool for rotary tillers, consisting of the part working into the soil, a spring connected to said part, said spring being fastened to a hub connected to the tilling shaft, in combination with a rubber' buffer as a damper for said tool and a 5- gulde fork as a lateral guide, a holding mem- 2. In connection with an elastically yieldv f of the guide fork being provided with a reber for the rubber buffer at the end of the guide fork.

5. The arrangement of an elastically yielding tool consisting of the part working into the soil, a tool spring and a clamping member I connecting the tool spring with the, said part,

in combination therewith a rubber buffer suitable to serve as an elastic stop for the clamping member, and a guide fork suitable to prevent a lateral deviation of the clamping member.

p 6. The arrangement of an elastically yielding tool, consisting of the part working into the soil, 2 tool spring and a clamping member connecting the tool spring with the said part,

in combination therewith a rubber bufi'er, a guide fork and a guldmg member embrac ing the rubber bufier at the top end and geiilig guided along the prongs of the guide 7. The arrangement of an elastically yielding tool, consisting of the part working into ing tool, consisting of the part working into the soil, a tool spring and a clamping member connecting the tool spring with the said part, in combination therewith a rubber buffer, a guide fork and a guiding member embracing the rubber buffer at the top end and being guided along the prongs of the guide fork,

said, guiding member guided on the prongs cess corresponding to the shape of the clamping member. 4

9. An elastically yielding tool, consisting of the part working into the soil, thetool spring connected to said part and fastened to lugs provided on the tool hub, in combination with a rubber buffer as an elastic stop for t tool and a guide fork as a lateral guide, said guide fork being fastened by means of special parts to lugs provided for fastening the tool spring.

10. An elastically yielding tool consisting of the part working'into the soil, the tool spring connected to said part and fastened to lugs provided on the tool hub, in combination with a rubber buffer asan elastic stop for the 'tool and a guide fork as a lateralguide f for the tool, said rubber bufi'er being fastened to the special parts provided for thefastening of the guide fork.

In testimony whereof we tures.

ADOLF SCHLHDT. GEORG PENEFF. 

